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First time anodizing questions

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  • First time anodizing questions

    I just finished anodizing the aluminum bar stock supplied with the deluxe kit from Caswell. I polished the bar and ran it through all of the steps as outlined in the manual including dying it black. I used the sput welder to make the connection (worked great) and decided to anodize the entire bar. Everything seems to have worked out fine. The aluminum bar looks fine.

    I have a few basic questions one being when I did the calculations for the 10x1x.1/8inch bar I came out with a current factor of 700 milliamps. The manual said to use 1 amp. Did I miscalculate or are we talking about horse shoes, do you round off the number to the nearest whole number. I’m using a constant current power supply and I believe PAR was reached as the manual said at around 90 minutes.

    I rigged up a simple agitator using ½” PVC pipe that I was able to place under the bar. Of course when the water is forced out of the pipe by the air, the agitator tends to float. Seeing as the GP plates that Caswell supplies are lead could I use small lead sinkers placed inside the pipe to weigh it down? I tried it out in a separate water tank and it worked.

    I ‘m using the four 300 watt heaters that Caswell supplies to heat my tanks. I found that I was rinsing and moving them from tank to tank in order to get the required temperature in a reasonable amount of time. Is there a higher wattage heater I could purchase for use with the deluxe kit?

    The anodizing sealant is made up with nickel acetate; the label warns that it could cause cancer. I’m using a chemical respirator during the boiling process but I’m still fearful of any remaining vapors. Would anodizing sealant LT be better and safer to use? Thanks again for your help.

  • #2
    Its good to hear that everything worked out for you, and on the first try. Good job.

    Your 22.75 bar required 711 mA to be anodized at 4.50 ASF, 700 mA provided 4.43 ASF, which is certainly close enough.

    The same bar would be 1.00 A at 6.33 ASF and 948 mA at 6.00 ASF.
    Recall that LCD operates over a range of 3 to 6 ASF. 4.5 ASF is simply in the middle of that range, and nothing more.

    The 16 AWG wire that came with your Sputwelder has a surface area of 0.17 square inches per inch submersed in the electrolyte. Technically, this area counts as part of the surface area of the work. But this can be safely ignored unless your work is very small, like less than 2

    Your lead sinkers won't hurt anything. I saw a small setup a while back where the agitation system was also the cathode, it was thin lead sheet that ran across the bottom, and up one side. in the middle of the sheet a "pipe" was formed, and perforated with lots of small holes. It was fed by plastic tubing from both ends. It worked great.

    You will need to be using about 100 gallons of sealant every day for years before the cancer risk becomes greater than what you breathe everyday driving to work. Government mandated warning labels.

    Get into the habit of keeping a notebook for your anodizations. Record the surface area of the work, the alloy, anodizing current, anodizing time, and 3 voltage measurements, startup voltage, voltage at 5 minutes, and voltage at completion. You will notice a pattern develop, if something goes wrong you will know it in time to correct it.


    • #3
      Thank you for all of the information. I'm still wondering about the higher rated heaters. I'm presently heating up some degreaser and stripper to prep for another run. I have three heaters in the degreaser and need about 3 more for the stripper in order to get the temperature up. I would like to purchase some higher rated heaters with controllable thermostats. Do you have any suggestions? Thanks again.


      • #4
        I'm not a Caswell employee so I can't say that I know this for sure:

        I believe Caswell will sell you more of the 300W heaters individually, and he has control units for them. You definitely want to use something with a ceramic (not glass and not steel) casing. I recall looking at some immersion heaters at an industrial supplier. What I remember is that Caswell's ceramic heaters were a pretty good deal compared to industrial units. Larger heaters may not be such a good idea if you're using 5 gallon buckets, they're much larger in size, and they must be completely immersed to be safe. I think you would be better off with multiple 300W heaters rather than fewer larger ones.

        If you want to heat up solutions real fast, get some cheap stainless steel stock pots and use a propane camp stove, one of the real big ones. Watch the ventilation (carbon monoxide) I use one of these to boil water for sealing (I only use nickel acetate if the part is too large for boiling) its right outside the walk in basement door. These should not be used indoors.


        • #5
          Thank you, I'll give Caswell a call in the morning.


          • #6
            Three 300W heaters should be able to bring 5 gallons to a boil, or close to it. Four are capable of bringing it to a hard boil. It may take up to a couple of hours, or more if the ambient temperature is colder than room temp. Using a cover on the containers helps measurably, and insulating the container does too. If you use 5 gallon buckets, you might try placing one inside another to help insulate it. Between that and an insulated cover, it will increase the heater effectiveness considerably.

            I don't know how hot you are wanting to get the stripper, but be aware as it get warm and then hot, the aggressiveness increases substantially with the temperature increase, so you might want to keep a close watch on the parts until you get used to it.


            • #7
              Thanks for the replies, what I’m trying to do is eliminate the need to rinse and move heaters from container to container during a run. At this point I have been following the advice of the Caswell manual regarding container temps. Thanks for the warning on the heated stripper solution. What would happen if I left a part in an over-heated tank of stripper for an extended amount of time? Thanks again!


              • #8
                It will dissolve.


                • #9
                  part didn't take dye

                  My part is so small it is only 2 square inches. But my rectifier minimum voltage is 3V. I measured the current and it displayed about 3A.

                  I know it is way too high for my small part.

                  My part never took the dye. Very bad first hand experience. I thought if it was too high of current density, it would burn.

                  Can anyone help?



                  • #10
                    Applying 3 amps to a part with 2 square inches of surface area results in a current density of 216 amps per square foot(!). The power supply you are using is not going to work at all with work that small. If you don't get a suitable power supply you have no chance at all.


                    • #11
                      Is that why the part didn't take dye? But they look a little bit matte after the anodizing process, not much different like burning or anything.